1. Field of the invention
The present invention relates to a surgical staple for discectomy by anterior approach to the cervical spine.
2. Description of the Background
Spinal stenosis is a medical condition in which the spinal canal narrows and compresses the spinal cord and nerves causing pain and neural degeneration. This is commonly due to spinal degeneration that naturally occurs with aging but can also be caused by spinal disc herniation (from trauma for example), osteoporosis, tumor or a variety of other causes. Stenosis may occur at any point along the spinal column but is more prevalent in the cervical and lumbar regions of the spine.
Cervical discectomy is a surgical procedure for treating spinal stenosis and disc herniation in the cervical region. Removal of the intervertebral disc and often the vertebral lamina (laminectomy) can relieve pressure from the spinal cord and neural structures. To maintain the stability of the spine in the absence of one or more intervertebral discs, spinal fusion is performed to immobilize the vertebrae.
Spinal fusion or spondylosyndesis is a surgical technique used to combine two or more vertebrae. Supplementary bone graft tissue is used in conjunction with the body's natural osteoblastic processes. A variety of approaches to fusion are available including posterolateral fusion which places the bone graft between the transverse processes in the back of the spine and anterior or posterior interbody fusion which places the bone graft between the vertebra in the area usually occupied by the intervertebral disc.
In most cases fusion is augmented by a process called fixation in which metallic screws, rods, plates or cages are implanted to stabilize the vertebra and facilitate bone fusion. The addition of hardware such as a cervical plate has been shown to maintain the stability of the graft/host junction increasing the chance of successful fusion. Conventional plates come in a basic construct of thin piece of metal and four screws that secure them to the bone. The typical screws are large and bulky. More recently narrow plates have emerged that use only two screws. There are benefits and drawback to both of these constructs.
Large plates and multiple screws offer a solid fixation but are bulky, use large screws, and require significant retraction for cases of multiple fixations which may lead into patients suffering from swallowing difficulties and possible changes in voice. Narrow plates with only two screws offer little fixation but minimize the hardware and intrusion. A variety of designs for spinal fixation devices have been proposed over the years although none have been entirely satisfactory.
It would be greatly advantageous to provide an anterior cervical staple for cervical fusion that: (1) allows for a more precise and a much smaller profile of fixation than prior art devices, (2) imposes less traction on the esophagus and trachea than prior art devices, (3) is lightweight, and (4) is inexpensive to manufacture and be applied for widespread use.